Abstract: An apparatus and method are disclosed for fast reroute (FRR) for native segment routing (SR) traffic. In one embodiment, a node receives a packet that includes a segment routing (SR) segment identifier (ID) stack. The node determines what type of segment is designated as the active segment in the segment ID stack. Based, at least in part on the type of active segment, the node selects an update routine out of several possible update routines and performs the selected update routine. The update routine modifies the segment ID stack.

Abstract: Various techniques can be used to avoid loops during network convergence after a topology change such as a failure. For example, a method can involve detecting a failure that disrupts an existing forwarding path between a node and a destination node; calculating at least one updated forwarding path from the node to the destination node; identifying a maximum time for at least a portion of the network to reach a post-convergence state with respect to the failure; until the maximum time has elapsed at the node, explicitly specifying at least a portion of the updated forwarding path in packet headers of any packets being sent from the node to the destination node; and after the maximum time has elapsed at the node, non-explicitly specifying the portion of the updated forwarding path in packet headers of any additional packets being sent from the node to the destination node.

Abstract: An apparatus and method for resolving services to nodal segments. The method involves receiving an advertisement. The advertisement includes a service address associated with a service. The method further involves identifying an originator node for the service, where the originator node is associated with a nodal segment identifier. The method further involves updating the advertisement. Updating the advertisement involves adding information identifying the originator node to the advertisement.

Abstract: An apparatus and method for enabling interoperability of segment routing (SR) enabled nodes and LDP enabled nodes in a network domain. In one embodiment, the method may include mapping a first node identifier (ID) to a first segment ID in memory, wherein the first node ID uniquely identifies a first node within a network domain, and wherein the first node is not SR enabled. A message is generated and subsequently transmitted directly or indirectly to another node within the network domain, wherein the message comprises the first node ID mapped to the first segment ID, and wherein the other node is SR enabled.

Abstract: In one embodiment, techniques are provided to generate a Border Gateway Protocol-Link State (BGP-LS) advertisement message comprising information configured to indicate topological information associated with a Layer 0 (L0) network, where the topological information includes information for connectivity within the L0 network that is available to a Layer 3 (L3) network. The advertisement message is sent to a node in the L3 network. The message sent from the L0 network is received at the node in the L3 network. The topological information in the message is analyzed in order to determine connections available to the L3 network, yet within the L0 network. A connection request is sent from the node in the L3 network to the L0 network and connections between the nodes in L3 network are established using available connections in the L0 network.

Abstract: Disclosed is an apparatus and method for segment routing using a remote forwarding adjacency identifier. In one embodiment, a first node in a network receives a packet, wherein the packet is received with a first segment-ID and another segment ID attached thereto. The first node detaches the first and the other segment IDs from the packet. Then the first node attaches a first label to the packet. Eventually, the first node forwards the packet with the attached first label directly to a second node in the network. In one embodiment, the other segment ID corresponds to a forwarding adjacency or tunnel label switched path between the first node and another node.

Abstract: Various techniques can be used to avoid loops during network convergence after a topology change such as a failure. For example, a method can involve detecting a failure that disrupts an existing forwarding path between a node and a destination node; calculating at least one updated forwarding path from the node to the destination node; identifying a maximum time for at least a portion of the network to reach a post-convergence state with respect to the failure; until the maximum time has elapsed at the node, explicitly specifying at least a portion of the updated forwarding path in packet headers of any packets being sent from the node to the destination node; and after the maximum time has elapsed at the node, non-explicitly specifying the portion of the updated forwarding path in packet headers of any additional packets being sent from the node to the destination node.

Abstract: In one embodiment, a controller device in a computer network domain learns border gateway protocol (BGP) egress peering segments from one or more border routers of the domain, and determines a selected flow to segment route via a particular egress peering segment, the selected flow from a given routing device within the domain to a given destination of a remote domain. As such, the controller device may then instruct the given routing device to segment route the selected flow via the particular egress peering segment. In another embodiment, an egress border router shares its BGP egress peering segments, and receives a flow to segment route. The egress border router may determine, from a segment route contained within the flow, to which particular egress peering segment of the border router to segment route the flow, and forwards the flow out of the domain via the particular egress peering segment.

Abstract: Hiding a service node in a network from a network topology is provided. In one embodiment, for example, an apparatus for hiding a service node in a network from a network topology, the apparatus comprising: a network interface; a processor; and one or more stored sequences of instructions which, when executed by the processor, cause the processor to perform: discovering a service node in a data network in accordance with a link-state protocol wherein the service node provides a network topology dependent service other than packet forwarding; establishing a link-state adjacency with the service node and one or more packet forwarding nodes in accordance with the link-state protocol; receiving a link-state advertisement; in response to identifying the link-state advertisement as an originating link-state advertisement sent from the service node, suppressing flooding of the received link-state advertisement to the one or more packet forwarding nodes.

Abstract: A system and method are disclosed for using segment routing (SR) in native IP networks. The method involves receiving a packet. The packet is an IP packet and includes an IP header. The method also involves updating the packet. Updating the packet involves writing information, including a segment routing segment identifier, to the destination address of the packet.

Abstract: In one embodiment, techniques are provided to generate a Border Gateway Protocol-Link State (BGP-LS) advertisement message comprising information configured to indicate topological information associated with a Layer 0 (L0) network, where the topological information includes information for connectivity within the L0 network that is available to a Layer 3 (L3) network. The advertisement message is sent to a node in the L3 network. The message sent from the L0 network is received at the node in the L3 network. The topological information in the message is analyzed in order to determine connections available to the L3 network, yet within the L0 network. A connection request is sent from the node in the L3 network to the L0 network and connections between the nodes in L3 network are established using available connections in the L0 network.

Abstract: An apparatus and method for enabling interoperability of segment routing (SR) enabled nodes and LDP enabled nodes in a network domain. In one embodiment, the method may include mapping a first node identifier (ID) to a first segment ID in memory, wherein the first node ID uniquely identifies a first node within a network domain, and wherein the first node is not SR enabled. A message is generated and subsequently transmitted directly or indirectly to another node within the network domain, wherein the message comprises the first node ID mapped to the first segment ID, and wherein the other node is SR enabled.

Abstract: A technique optimizes routing of application data streams on an Internet Protocol (IP) backbone in a computer network. According to the novel technique, a client router learns of server states (e.g., number of pending requests, etc.) of a plurality of application servers and also determines metrics of intermediate links between the application servers and the client router (intermediate link metrics), e.g., particularly link metrics in a direction from the application servers to the client router. Upon receiving an application request from an application client (“client request”), the client router determines to which of the application servers the client request is to be sent based on the server states and intermediate link metrics, and sends the client request accordingly.

Abstract: Various techniques can be used to advertise adjacency segment identifiers (IDs) within a segment routing (SR) network. For example, a method, performed by a first node, can involve identifying an adjacency segment between a first node and a second node; assigning an identifier to the adjacency segment; and sending an Intermediate-System-to-Intermediate-System (IS-IS) hello (IIH) message to another node. The adjacency advertisement includes the identifier. If the adjacency segment is part of a LAN, the IIH message can be sent to a designated node that aggregates adjacency segment ID advertisements for the other nodes on the LAN.

Abstract: An apparatus and method for path creation element driven dynamic setup of forwarding adjacencies and explicit path. In one embodiment of the method, a node receives an instruction to create a tunnel between the node and another node. The node creates or initiates the creation of the tunnel in response to receiving the instruction, wherein the tunnel comprises a plurality of nodes in data communication between the node and the other node. The node maps a first identifier (ID) to information relating to the tunnel. The node advertises the first ID to other nodes in a network of nodes.

Abstract: An apparatus and method for resolving services to nodal segments. The method involves receiving an advertisement. The advertisement includes a service address associated with a service. The method further involves identifying an originator node for the service, where the originator node is associated with a nodal segment identifier. The method further involves updating the advertisement. Updating the advertisement involves adding information identifying the originator node to the advertisement.

Abstract: An apparatus and method are disclosed for fast reroute (FRR) for native segment routing (SR) traffic. In one embodiment, a node receives a packet that includes a segment routing (SR) segment identifier (ID) stack. The node determines what type of segment is designated as the active segment in the segment ID stack. Based, at least in part on the type of active segment, the node selects an update routine out of several possible update routines and performs the selected update routine. The update routine modifies the segment ID stack.

Abstract: A method and apparatus for forwarding packets through a network domain that contains nodes that are label distribution protocol (LDP) enabled and nodes that are segment routing (SR) enabled. In one embodiment, the method may include a network node receiving a packet with a label attached thereto. The node swaps the label with a segment identifier (ID). The node then forwards the packet to an SR node. In another embodiment, the method may include a network node receiving a packet with a segment ID attached thereto. The node swaps the segment ID with a label. The node then forwards the packet to an LDP enabled node.

Abstract: An apparatus and method for using indexed segment identifiers in segment routing. An example method involves receiving a globally unique index value at a node. The method also involves receiving a base value at the node, where the base value comprises a segment routing value configured to identify a nodal segment. The method then involves calculating a segment identifier based on the index value and the base value.

Abstract: A technique optimizes routing of application data streams on an Internet Protocol (IP) backbone in a computer network. According to the novel technique, a client router learns of server states (e.g., number of pending requests, etc.) of a plurality of application servers and also determines metrics of intermediate links between the application servers and the client router (intermediate link metrics), e.g., particularly link metrics in a direction from the application servers to the client router. Upon receiving an application request from an application client (“client request”), the client router determines to which of the application servers the client request is to be sent based on the server states and intermediate link metrics, and sends the client request accordingly.